In that light, there’s now genetic evidence for a population bottleneck around 8000 years ago, specific to men. The effect was quite large: “for every 17 female humans who reproduced at this time, only one male human managed to pass along his DNA.” It all sounds very Freudian:

The members of the group were subject to ties just as we see them to-day, but the father of the primal horde was free. His intellectual acts were strong and independent even in isolation, and his will needed no reinforcement from others. Consistency leads us to assume that his ego had few libidinal ties; he loved no one but himself, or other people only in so far as they served his needs. To objects his ego gave away no more than was barely necessary.He, at the very beginning of the history of mankind, was the Superman whom Nietzsche only expected from the future. Even to-day the members of a group stand in need of the illusion that they are equally and justly loved by their leader; but the leader himself need love no one else, he may be of a masterly nature, absolutely narcissistic, but self-confident and independent. We know that love puts a check upon narcissism, and it would be possible to show how, by operating in this way, it became a factor of civilisation.
The primal father of the horde was not yet immortal, as he later became by deification. If he died, he had to be replaced; his place was probably taken by a youngest son, who had up to then been a member of the group like any other. There must therefore be a possibility of transforming group psychology into individual psychology; a condition must be discovered under which such a transformation is easily accomplished, just as it is possible for bees in case of necessity to turn a larva into a queen instead of into a worker. One can imagine only one possibility: the primal father had prevented his sons from satisfying their directly sexual tendencies; he forced them into abstinence and consequently into the emotional ties with him and with one another which could arise out of those of their tendencies that were inhibited in their sexual aim. He forced them, so to speak, into group psychology. His sexual jealousy and intolerance became in the last resort the causes of group psychology.

While testosterone has its advantages, it also compromises immune function. Because living in modern civilization involves a lot less exposure to parasites, Western people have something like 30% more circulating testosterone. Macho, hyper-competitive culture really is regressive, in that too much testosterone was preventing the Great Leap Forward.